Wood heat in America has been an energy and money saving phenomenon that has been overlooked for years. Currently, 1-in-50 American homes, or 2%, use wood as a primary heat source. 1Wood can also be used to partially replace an existing heat source, with 8% of U.S. homes reporting the use of stoves and fireplace inserts as secondary heating appliances. 2Biomass 3fuel can be self harvested or purchased for much less than the cost of most conventional fuels, meaning that its use for residential heating represents one of the most cost effective ways to utilize one of America’s most abundant renewable energy sources. Furthermore, unlike other uses of biomass, such as electricity and liquid fuel that only utilize 25-50% of the potential energy contained in the fuel, biomass used for heat can capture up to 90% of this energy for its use in heating the home (Fig 1).
Figure 1: Relative Biomass End-use Efficiencies (Pinchot Institute for Conservation) * AWC is advanced wood combustion; CHP is combined heat and power; co-firing is with both coal and biomass)
Reliance on wood for home heating is not exclusive to the more northerly regions of the US; New Mexico and Arkansas rank in the top fifteen wood burning states. Wood burning varies greatly across the states and communities. Maryland, for example, has a state-wide wood use rate around the national average, but has counties such as Garret County with 12.4% of the population using wood as a primary heat source. 4Vermont has the highest state-wide percentage of wood use with 11.8% of households relying on wood as a primary heating source (Fig. 2), and 32% using wood as a secondary heating source.5
Figure 2: 2009 Wood burning as the primary heat source (U.S. Census Bureau)
Residential wood heat has been on the rise in the majority of U.S. states since 2000 (Fig. 3). Wood use has always been very responsive to the prices of other fuels; historically the use of wood for heat has been closely correlated with high oil prices. Prior to 1940, 3-in-4 households used coal or wood for heating, but in subsequent decades natural gas and electricity came to dominate. 6Fortunately, the use of coal as a home heating fuel has diminished over time, although a certain irony exists in the fact that the majority of electricity used for heating is sourced from coal burning power plants.
Globally, interest in wood for home heating increased in response to the 1970’s oil crisis, while today there is renewed interest due to the fuel price volatility and greater environmental considerations. 7Unlike fossil fuels, wood prices remain relatively stable over time, meaning that an investment in an efficient wood heating appliance can help to hedge against spikes in fossil fuel prices. This issue is especially poignant in low income communities, where an unexpected increase in heating prices can severely strain tight budgets.
In the last ten years, only twelve states have seen a decrease in wood use as a primary source of heat, while thirty one states have seen an increase in wood use (Fig. 3). 8The states where wood has declined the most are primarily the south-eastern states. This trend is possibly due to the relatively low home heating burden of that geographic area. It is likely that the low yearly requirement for home heating does not necessitate the price saving switch to wood heat, while switching from wood often yields large dividends in time and effort saved.
Figure 3: Wood use change in the US between 2000-2009 (US Census Bureau)